Orthopedic augment with cement trough containing projections

ABSTRACT

Systems, devices, and methods are provided for orthopedic implants. The implants may include a base member, such as an acetabular shell or an augment, that is configured to couple with an augment, flange cup, mounting member, or any other suitable orthopedic attachment. An implant may include abuse member that has at least two projections with a gap between the projections. The gap between the projections allows the implant to be implanted around another implanted component, such as around a bone screw of an acetabular shell. The implant may include a fixation element, such as a screw or a cement trough, on one or more projections to couple the implant to an implanted acetabular shell. The implant may also include timing marks to facilitate alignment with corresponding marks on another implanted component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/616,525, filed Feb. 6, 2015, now U.S. Pat. No. 9,468,530, which is adivision of U.S. patent application Ser. No. 13/156,248, filed Jun. 8,2011, now U.S. Pat. No. 8,979,926, which claims the benefit of U.S.Provisional Patent Application No. 61/352,705, filed Jun. 8, 2010, U.S.Provisional Application No. 61/352,722, filed Jun. 8, 2010, U.S.Provisional Application No. 61/422,903, filed Dec. 14, 2010, and U.S.Provisional Application No. 61/466,817, filed Mar. 23, 2011, which arehereby incorporated by reference herein in their entireties.

BACKGROUND

Joints often undergo degenerative changes due to a variety of reasons.When joint degeneration becomes advanced or irreversible, it may becomenecessary to replace the natural joint with a prosthetic joint.Artificial implants, including hip joints, shoulder joints, and kneejoints are widely used in orthopedic surgery. Specifically, hip jointprostheses are common. The human hip joint acts mechanically as a balland socket joint, wherein the ball-shaped head of the femur ispositioned within the socket-shaped acetabulum of the pelvis. Variousdegenerative diseases and injuries may require replacement of all or aportion of a hip using synthetic materials, typically metals, ceramics,or plastics.

More particularly, natural hips often undergo degenerative changes,requiring replacement of the hip joint with a prosthetic joint. Often,the hip is replaced with two bearing surfaces between the femoral headand the acetabulum. The first bearing surface is typically a prosthesisshell or acetabular cup, which may be formed of metal, ceramic material,or as otherwise desired. A liner (conventionally formed of polyethylenematerial such as ultra high molecular weight polyethylene, a ceramicmaterial, or in some cases, even a metal liner) is then fit tightlywithin the shell to provide an inner bearing surface that receives andcooperates with an artificial femoral head in an articulatingrelationship to track and accommodate the relative movement between thefemur and the acetabulum.

The cup (or a cup and liner assembly) is typically fixed either byplacing screws through apertures in the cup or by securing the cup withcement. In some cases, only a liner is cemented in a patient due to poorbone stock. In other cases, a cup having a porous surface may be pressfit into the reamed acetabular surface.

It may become necessary to conduct a second or subsequent surgery inorder to replace a prosthetic joint with a (often larger) replacementjoint. Such surgeries often become necessary due to further degenerationof bone or advancement of a degenerative disease, requiring removal offurther bone and replacement of the removed, diseased bone with a largeror enhanced prosthetic joint, often referred to as a revisionprosthesis. For example, bone is often lost around the rim of theacetabulum, and this may provide less rim coverage to securely place apress-fit cup. Such surgeries may thus be referred to as revisionsurgeries.

In acetabular revision surgery, an acetabular prosthesis generallyincludes additional mounting elements, such as augments, flanges, hooks,plates, or any other attachment or mounting points or members thatprovide additional support and/or stability for the replacementprosthesis once positioned. These additional mounting or attachmentmembers are often required due to bone degeneration, bone loss, or bonedefects in the affected area (in this instance, the hip joint).

Various types of these mounting members (which term is intended toinclude but not be limited to flanges, blades, plates and/or hooks) maybe provided in conjunction with a prosthesis system in order to help thesurgeon achieve optimal fixation, non-limiting examples of which includeiliac flanges (providing securement and fixation in and against theilium region of the pelvis), ischial blades (providing securement andfixation in and against the ischium), and obturator hooks (providingsecurement and inferior fixation by engaging the obturator foramen).Although there have been attempts to provide such mounting attachmentswith modularity, the solutions to date have generally fallen short ofproviding true modularity. Instead, they typically provide a fewdiscrete positions at which the mounting members may be positioned,without providing the surgeon a fuller range of decision options.

Additionally, in some primary surgeries and more often in revisionsurgeries, the acetabulum may have a bone defect or void that thesurgeon must fill with bone grafts before inserting a new shell. Thiscan be time consuming and expensive, and may subject the patient toadditional health risks. Some techniques use an augment in connectionwith the acetabular which can be coupled to or otherwise attached to theouter surface of the shell.

With current augments, the surgeon can attach the augment to the boneand then implant the cup. However, many acetabular shells rely on bonescrews to achieve proper fixation and the augment often gets in the wayof a screw. In short, surgeons need the freedom to place screws in thebest location, but this compromises their ability to use augments. Withcurrent systems, it also takes an increased amount of time surgical timeto trial the component orientation and that try to find good bonefixation for the cup. The surgeon will often have to free-hand theamount of bone removed while estimating the size of augment needed. Inthe cases where bone is often deficient, surgeons are hesitant to takeaway any more bone than necessary.

Various additional features and improved features intended for use andapplication with various types of joint implants are also describedherein, such as improved bone screws, improved coatings, and variousaugment removal and insertion options.

SUMMARY

Disclosed herein are systems, devices, and methods for providing modularorthopedic implants. The implants may include a base member, such as anacetabular shell or an augment, that is configured to couple with anaugment, flange cup, mounting member, any other suitable orthopedicattachment, or any combinations thereof. Mounting members include, forexample, flanges, blades, hooks, and plates. In some embodiments, theorthopedic attachments may be adjustably positionable about the basemember or other attachments thereby providing modularity for assemblingand implanting the device. Various securing and/or locking mechanismsmay be used between the components of the implant. In certainembodiments, the orthopedic attachments are removably coupled to thebase member or other components. In certain embodiments, the orthopedicattachments are integrally provided on the base member or othercomponents, yet may still be adjustably positionable thereabout. In someembodiments, expandable augments, base members, or other bone fillingdevices are provided. In some embodiments, surface features are providedthat create friction and allow for surrounding bone ingrowth at theinterface of the implants and a patient's bone.

Systems, devices, and methods described herein provide implants having aplurality of projections and optional fixation elements. In certainembodiments, an orthopedic augment includes a base member to which atleast two projections are coupled, the at least two projections having agap therebetween, and a fixation element provided on one or more of theat least two projections. The fixation element may be a cement trough.In certain embodiments, the base member is shaped to couple with animplant. For example, a first surface of the base member that contactsthe implant may be substantially arcuate. The at least two projectionsmay be disposed in substantially the same direction. The length of theat least two projections may be substantially the same, or the length ofone of the at least two projections may be different than the respectivelength of another of the at least two projections. In some embodiments,the base member includes one or more fixation elements such as screwholes configured to receive a fastener. In some embodiments, the basemember includes a connection element configured to receive a driverhandle for placing the orthopedic augment into a patient's joint. Insome embodiments, the base member includes timing marks configured toalign with corresponding timing marks on an implant. In someembodiments, the augment may further include flanges, blades, plates, orhooks attached thereto.

In certain embodiments, a method of implanting an orthopedic device in apatient's joint may include placing an implant within the patient'sjoint, the implant secured to the joint via a fixation device, preparinga space in the patient's bone proximate the implant and the fixationdevice, providing an augment that includes at least two projectionshaving a gap therebetween, and inserting the augment into the preparedspace by positioning the augment around the fixation member such thatthe fixation member extends through the gap between the at least twoprojections of the augment. The method may further include forming acement trough on one or more of the at least two projections, andsetting the augment by pouring cement into the cement trough. In someembodiments, the method includes setting the augment using screws. Thepreparing may include rasping or reaming the patient's bone with abroach. The broach may have approximately the same cross-sectionalprofile as the augment. In some embodiments, the amount of bone removedmay be limited by using a depth stop disposed on the broach. Theinserting may include attaching the augment to a driver handle forpositioning the augment into the prepared space. The method may furtherinclude aligning timing marks disposed on the augment with timing marksdisposed on the implant. In some embodiments, the augment furthercomprises flanges, blades, plates, or hooks attached thereto. In someembodiments, the placing including mounting an acetabular shell or cagewithin the patient's acetabulum.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIGS. 1 and 2 show a front perspective view and a back view,respectively, of an illustrative augment;

FIG. 3 shows a top plan view of an augment illustratively installed onan acetabular shell;

FIGS. 4-7 illustrate exemplary methods for installing an augment into apatient's joint;

FIG. 8 shows a front perspective view of an illustrative augment havingthree projections;

FIG. 9 shows a top plan view of an augment having an illustrativeflange; and

FIG. 10 shows a partial cross-section elevation view of an illustrativeaugment with a flange installed in an acetabulum.

DETAILED DESCRIPTION

To provide an overall understanding of the systems, devices, and methodsdescribed herein, certain illustrative embodiments will be described.Although the embodiments and features described herein are specificallydescribed for use in connection with acetabular systems, it will beunderstood that all the components, connection mechanisms, adjustablesystems, fixation methods, manufacturing methods, coatings, and otherfeatures outlined below may be combined with one another in any suitablemanner and may be adapted and applied to medical devices and implants tobe used in other surgical procedures, including, but not limited to:spine arthroplasty, cranio-maxillofacial surgical procedures, kneearthroplasty, shoulder arthroplasty, as well as foot, ankle, hand, andother extremity procedures.

Various implants and other devices described herein in their variousembodiments may be used in conjunction with any appropriatereinforcement material, non-limiting examples of which include bonecement, appropriate polymers, resorbable polyurethane, and/or anymaterials provided by PolyNovo Biomaterials Limited, or any suitablecombinations thereof. Further non-limiting examples of potentialmaterials that may be used are described in the following references:U.S. Patent Application Publication No. 2006/0051394, entitled“Biodegradable Polyurethane and Polyurethane Ureas,” U.S. PatentApplication Publication No. 2005/0197422, entitled “BiocompatiblePolymer Compositions for Dual or Multi Staged Curing,” U.S. PatentApplication Publication No. 2005/0238683, entitled “BiodegradablePolyurethane/Urea Compositions,” U.S. Patent Application Publication No.2007/0225387, entitled “Polymer Compositions for Dual or Multi StagedCuring,” U.S. Patent Application Publication No. 2009/0324675, entitled“Biocompatible Polymer Compositions,” U.S. Patent ApplicationPublication No. 2009/0175921, entitled “Chain Extenders,” and U.S.Patent Application Publication No. 2009/0099600, entitled “High ModulusPolyurethane and Polyurethane/Urea Compositions.” Each of the priorreferences is incorporated by reference herein in its entirety.

FIGS. 1 and 2 are a front perspective view and a back view,respectively, of an augment according to certain embodiments. In FIGS. 1and 2, augment 910 is in the shape of a staple and is provided with anumber of projections and optional fixation elements. For example,augment 910 includes two projections 920 extending from a base portionor member 970, although it is possible that the augment 910 may havethree or more projections that extend from a base member as describedbelow. As shown, the projections 920 may be disposed in substantiallythe same direction from the augment 910 defined by the respective axisof each projection, with a gap 925 between the two projections 920. Incertain embodiments the projections 920 may be angled or otherwiseoffset such that the projections 920 are not disposed in the samedirection from the augment 910; however, there may still preferably be agap disposed between the two projections 920. Furthermore, although thelength of the projections 920 is shown as being substantially the same,it will be understood that the length of one of the projections 920 maybe different than the respective length of the other projection. Thebase member 970, or the projections 920, or both, may have a surfacethat is substantially arcuate, for example, in order to complement anouter curved surface of an acetabular shell or other implant.

Optional fixation elements include screw holes 930 and cement troughs960. The fixation elements fix the augment 910 in place when implanted.Each fixation element may connect the augment 910 to a patient's bone,an acetabular shell, or both. The augment 910 may also include aconnection element 940 on base member 970, for example, at the centertop of the augment 910. In certain embodiments, connection element 940is a threaded opening that may be attached to the end of a driver handle(e.g., driver handle 1060 of FIG. 7) for assisting with the implantationof the augment 910. However, the connection element 940 may be a taperedconnection, a quick-connect, or any other type of fitting. The augment910 may further include timing marks 950 to allow the augment 910 to beproperly placed within the hip bone. Installation of the augment 910 isdescribed in further detail below.

FIG. 3 is a top view of an augment installed on an acetabular shell.Augment 860 may be similar to augment 910. As shown, augment 860 ispositioned next to acetabular shell 862 such that timing marks 864disposed on the augment 860 are aligned with timing marks 866 disposedon the acetabular shell 862. The base member of augment 860 has anarcuate surface that contacts the complementary curved outer surface ofthe acetabular shell 862. As described above, an augment such as augment860 may be fixed to the acetabular shell 862, a patient's bone, or both,via optional fixation elements such as screw holes and cement troughs.

FIGS. 4-7 illustrate exemplary methods for installing an augment 910into a patient's joint according to certain embodiments.

FIG. 4 is a cross-sectional elevation drawing of an acetabulum 990 andan acetabular shell 1010. The acetabulum 990 would have been prepared toreceive the shell 1010 by reaming, rasping or the like. Bone screws 1020or other appropriate fixation devices have also been installed to secureshell 1010. Also shown is bone deficient area 1000. This area 1000 is avoid space extending from the outer wall of the acetabular shell 1010 tothe acetabulum 990.

In FIG. 5, the acetabulum 990 is prepared for the augment 910 by use ofbroach 1030. The broach 1030 can be of any kind useful for rasping orreaming bone. For use with the augments described herein, the broach1030 is typically provided with a depth stop 1040. Depth stop 1040prevents the broach 1030 from removing too much bone by catching, forexample, on the rim of acetabular shell 1010. The broach 1030 may haveroughly the same cross-sectional profile and overall shape as theaugment 910 and is typically sized to allow the augment 910 to bewedge-fitted into bone deficient area 1000. The broach 1030 may alsohave a slot provided therein to allow the broach 1030 to slide on eitherside of the installed screw 1020 to clear away bone on both sides of thescrew 1020.

In FIG. 6, the acetabulum 990 has been prepared for the augment 910.Bone deficient area 1000 has been replaced with prepared space 1050between the acetabulum 990 and the acetabular shell 1010, the preparedspace including screw 1020.

The next step in the procedure is illustrated in FIG. 7. The augment 910is attached to driver handle 1060 and inserted into prepared space 1050.During insertion, the surgeon matches the timing marks 950 on the top ofthe augment 910 to timing marks (e.g., timing marks 886) on theacetabular shell 1010 to ensure that bone screw 1020 is avoided. Theaugment 910 is inserted into the prepared space by positioning theaugment around the screw 1020 (or any other fixation member) such thatthe screw 1020 extends through the gap 925 between projections 920 ofaugment 910. Once the augment 910 has been pushed into place by hand, itmay be tapped into its final position with a hammer. If the surgeondesires, the surgeon may then fix the augment 910 even further by usingaugment screws placed into screw holes 930 and then into the patient'sbone. Alternatively or additionally, the surgeon can pour bone cementdown the troughs 960 illustrated in FIG. 1. The cement may bind theaugment 910 to the acetabular shell 1010, the patient's bone, or both.

In some embodiments, the augment 910 is held in place solely by afriction fit. In some embodiments, fixation devices like bone screws orcement may be used to secure augment 910 in place, for example, viascrew holes 930 or cement troughs 960, respectively. Any kind of bonescrew or cement familiar to one of ordinary skill in the art may beused.

FIG. 8 shows a front perspective view of an augment having threeprojections extending from a top or base member according to certainembodiments. For example, augment 910′ may be similar to augment 910 ofFIG. 1, but augment 910′ includes three projections 920′ extending fromthe top member 970′. It will be understood that in certain embodimentsan augment may include more than three projections.

In some embodiments, the augments described above may be provided withflanges, blades, plates, hooks, any other suitable mounting members, orany combinations thereof. For example, FIG. 9 shows a top plan view ofan augment 1080 with flange 1090. Flange 1090 may provide additionalsupport for the augment 1080 on the outside of the acetabulum (e.g.,acetabulum 1092 of FIG. 10). FIG. 10 illustrates a partial cross-sectionelevation view of an augment 1080 installed in acetabulum 1092 withflange 1090 having bone screw 1094 provided therethrough.

The augments described herein may be made of a number of materials,including Titanium, Cobalt-Chromium, Zirconium oxide, any otherbiocompatible materials or alloys that have the appropriate strength,resistance to wear, etc., or any combinations thereof. The augments mayalso be made fully porous or partially porous to allow for greater bonein-growth, for example, and the augments may be coated withhydroxyapatite or any other bone-promoting agents or combinationsthereof.

The embodiments described preferably above allow a surgeon to implantthe acetabular shell or cup first and gain desired screw fixation andthen prepare the bone minimally to fit a desired augment, This enablesthe surgeon to get the desired fixation for the acetabular shell withoutcompromising the surgeon's ability to use an augment. An additionaladvantage is that the surgeon removes no more bone than is necessary.

The foregoing is merely illustrative of the principles of thedisclosure, and the systems, devices, and methods can be practiced byother than the described embodiments, which are presented for purposesof illustration and not of limitation. It is to be understood that thesystems, devices, and methods disclosed herein, while shown for use inacetabular systems, may be applied to medical devices to be used inother surgical procedures including, but not limited to, spinearthroplasty, cranio-maxillofacial surgical procedures, kneearthroplasty, shoulder arthroplasty, as well as foot, ankle, hand, andextremities procedures.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombinations (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

What is claimed is:
 1. An orthopedic augment comprising a plurality ofprojections and a base member, each of the plurality of projectionsextending from the base member and defining a gap between two adjacentprojections of the plurality of projections, each of the plurality ofprojections further containing a trough formed in an implant-contactsurface of the orthopedic augment, the orthopedic augment furthercomprising a bone-contact surface, the bone-contact surface and theimplant-contact surface positioned on opposite sides of the orthopedicaugment, wherein each trough has an open end defined in the base memberand a closed end and extends continuously along the implant-contactsurface from the open end to the closed end formed in theimplant-contact surface, and wherein the implant-contact surface of theorthopedic augment includes an inward arcuate shaped profile that isshaped for placement against an outward arcuate shaped profile of anouter surface of an implant, the bone-contact surface is shaped forplacement against a prepared bone surface, and each trough defines acavity for receiving cement through the open end.
 2. The orthopedicaugment of claim 1, wherein the each trough comprises a longitudinalwall formed in the implant-contact surface between the open end and theclosed end.
 3. The orthopedic augment of claim 2, wherein thelongitudinal wall of each trough defines a concave surface extending alength of each trough.
 4. The orthopedic augment of claim 2, wherein theorthopedic augment is configured for cement to be contained in thecavity of each trough by the corresponding longitudinal wall of therespective trough, the corresponding closed end of the respectivetrough, and the outer surface of the implant.
 5. The orthopedic augmentof claim 1, wherein the plurality of projections comprises a firstprojection and a second projection, the first projection having a firsttrough formed in the implant-contact surface, and the second projectionhaving a second trough formed in the implant-contact surface.
 6. Theorthopedic augment of claim 5, wherein the second trough is parallel tothe first trough.
 7. The orthopedic augment of claim 5, wherein thesecond trough has a different respective length than a length of thefirst trough.
 8. The orthopedic augment of claim 5, wherein each troughcavity is not fluidically connected with any other trough cavity.
 9. Theorthopedic augment of claim 8, wherein the plurality of projectionsfurther comprises a third projection having a third trough formed in theimplant-contact surface.
 10. The orthopedic augment of claim 1, whereinthe bone-contact surface has an outward arcuate shaped profile.
 11. Theorthopedic augment of claim 1, wherein the orthopedic augment is atleast partially porous.
 12. The orthopedic augment of claim 1, whereinthe orthopedic augment is fully porous.